High pressure pipes are commonly used for transporting potable water, effluent, gas, oil, industrial materials, and other such flowable materials. A common component of typical high pressure pipe is high-density polyethylene (HDPE). HDPE is one of the most chemically inert plastics and is, therefore, both chemical-resistant and corrosion-resistant. In addition, HDPE has excellent mechanical properties that tend to be desirable in pressure pipe applications. Based on the polymer strength, pressure pipes can be classified in different categories, such as PE63, PE80 or PE100. In general, the higher the number, the better the crack propagation resistance and the longer the life service the pressure pipe will have under high pressure.
In making such conventional pressure pipe, granules of HDPE are compounded with a carbon black masterbatch, another main component of pressure pipes. Carbon black masterbatch is a mixture of carbon black, polyethylene resin, and possibly additives. The carbon black concentration or loading in conventional masterbatch is in the range of 25% to 40%, with the balance of the mixture being polyethylene resin and various conventional additives. The polyethylene resin is typically a polyolefin carrier such as a low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE) or HDPE.